[opensourcedex]

core is a free, open source social networking project written in PHP and released under AGPL-3.0. It has 8,833 GitHub stars, 2,059 forks and 141 open issues, and was last pushed 13 hours ago. On this registry it ranks #8 of 44 tracked projects in Social Networking, with 5 head-to-head comparisons available.

What is core?

What it is

ownCloud Core is the server-side component of ownCloud Classic, an open-source file platform written in PHP and released under the AGPL-3.0 license. It provides file storage, synchronization, and sharing, and it ships WebDAV, CalDAV, and CardDAV servers alongside a plugin architecture that other ownCloud apps extend. The repository is the main one for ownCloud Classic and serves as the foundation for apps such as Activity, Calendar, and Contacts. Development is stewarded by the Kiteworks Open Source Program Office under the ownCloud brand.

The concrete problem it solves is giving an organization a self-hosted place to keep files and calendars that it controls itself, rather than renting that storage from a third party. It handles the server side of syncing files across devices, sharing them with other users and groups, and exposing them through standard protocols and a REST API so that clients and integrations can talk to it. The README states the platform is trusted by over 200 million users worldwide.

Key capabilities

  • File storage, synchronization, and sharing as the core server function.
  • WebDAV, CalDAV, and CardDAV servers for file, calendar, and contact access.
  • A plugin architecture that apps such as Activity, Calendar, and Contacts extend.
  • User and group management built into the server.
  • Encryption support and external storage backends.
  • A comprehensive REST API for clients and integrations.
  • Support for MySQL, MariaDB, PostgreSQL, and SQLite databases.

Who uses it and how

  • Organizations that need self-hosted file sync and share deploy the server and connect desktop and mobile clients to it.
  • Administrators manage users and groups through the server, then grant access to shared folders.
  • Teams extend the deployment with apps from the ownCloud ecosystem, such as Calendar and Contacts, which build on the core.
  • Integrators use the REST API and the DAV endpoints to connect external tools and clients.
  • Deployments that need more capacity attach external storage backends and enable encryption.

Getting started

The server is available as a Docker image, owncloud/server, on Docker Hub, and the official installation manual at doc.owncloud.com covers installation of ownCloud Classic. For development builds, the prerequisites are Composer v2 plus Yarn and Node.js version 14 or higher, and the build runs with make.

When to use it — and when not to

Choose ownCloud Core when a self-hosted file, calendar, and contacts server with standard DAV protocols and a plugin ecosystem is the requirement. A self-hoster must operate the PHP runtime and one of the supported databases, and must follow the documented installation and upgrade path. Note that this repository is ownCloud Classic; the README points to ownCloud Infinite Scale (oCIS) as the next-generation platform, so new deployments should weigh which of the two lines they intend to run

project readme (upstream, from github) — read inline

ownCloud Core

License ownCloud OSPO Docker Hub

ownCloud Core is the server-side component of ownCloud Classic, providing file storage, synchronization, and sharing trusted by over 200 million users worldwide. It includes WebDAV, CalDAV, and CardDAV servers, a plugin architecture for apps, user and group management, encryption support, external storage backends, and a comprehensive REST API. The server runs on PHP with support for MySQL, MariaDB, PostgreSQL, and SQLite databases.

Part of ownCloud Classic

This is the main repository for ownCloud Classic. It is the foundation that apps like Activity, Calendar, Contacts, and many others extend. The server is available as a Docker image on Docker Hub.

For the next-generation ownCloud platform, see ownCloud Infinite Scale (oCIS).

Getting Started

For installing ownCloud Classic, see the official installation manual.

Development Build Prerequisites

  • Composer v2
  • Yarn and Node.js (v14 or higher)
make

Documentation

Community & Support

Star this repo and Watch for release notifications!

Contributing

We welcome contributions! Please read the Contributing Guidelines and our Code of Conduct before getting started.

Workflow

  • Rebase Early, Rebase Often! We use a rebase workflow. Always rebase on the target branch before submitting a PR.
  • Dependabot: Automated dependency updates are managed via Dependabot. Review and merge dependency PRs promptly.
  • Signed Commits: All commits must be PGP/GPG signed. See GitHub's signing guide.
  • DCO Sign-off: Every commit must carry a Signed-off-by line:
    git commit -s -S -m "your commit message"
  • GitHub Actions Policy: Workflows may only use actions that are (a) owned by owncloud, (b) created by GitHub (actions/*), or (c) verified in the GitHub Marketplace.

Translations

Help translate this project on Transifex:

Please submit translations via Transifex -- do not open pull requests for translation changes.

Security

Do not open a public GitHub issue for security vulnerabilities.

Report vulnerabilities at **** -- see SECURITY.md.

Bug bounty: YesWeHack ownCloud Program

License

This project is licensed under the AGPL-3.0.

About the ownCloud OSPO

The Kiteworks Open Source Program Office, operating under the ownCloud brand, launched on May 5, 2026, to steward the open source ecosystem around ownCloud's products. The OSPO ensures transparent governance, license compliance, community health, and sustainable collaboration between the open source community and Kiteworks, which acquired ownCloud in 2023.

  • OSPO Home:
  • GitHub:
  • ownCloud:

For questions about the OSPO or licensing, contact [email protected].

License Migration to Apache 2.0

The OSPO is driving a strategic relicensing of ownCloud repositories toward the Apache License 2.0, following the Apache Software Foundation's third-party license policy.

Individual repositories will migrate as their audit is completed. The LICENSE file in each repo reflects its current license status (not the target).

Current license: AGPL-3.0 (Category X per Apache policy -- cannot be included in Apache-2.0 works).

Migration prerequisites for this repository:

  • CLA/DCO coverage: All past contributors must have signed agreements permitting relicensing
  • Copyleft dependency audit: All AGPL/GPL dependencies must be replaced or isolated
  • KDE heritage review: Any code with KDE-era copyrights requires legal analysis
  • Complete relicensing: AGPL-3.0 is a strong copyleft license; migration requires full relicensing of all files, not just a header change

Frequently asked questions

Is core free to use?

core is open source under the AGPL-3.0 licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does core do?

:cloud: ownCloud web server core (Files, DAV, etc.)

What is core written in?

core is primarily written in PHP. Its source is publicly available at https://github.com/owncloud/core, and it has 8,833 GitHub stars.